Mozilla has announced plans to integrate its Firefox web browser with Metro for Windows 8 - including Gecko. "Windows 8 contains two application environments, 'Classic' and 'Metro'. Classic is very similar to the Windows 7 environment at this time, it requires a simple evolution of the current Firefox Windows product. Metro is an entirely new environment and requires a new Firefox front end and system integration points. The feature goal here is a new Gecko based browser built for and integrated with the Metro environment. Firefox on Metro, like all other Metro apps will be full screen, focused on touch interactions, and connected to the rest of the Metro environment through Windows 8 contracts." I haven't checked - does Microsoft allow different rendering engines?

They would probably need a new plugin model that is itself suited for WinRT though, since the APIs and application lifecycle models are so different (and NPAPI/ActiveX/whatever plugins of today are really very general applications with some added hooks). Once that is in place though there is no real reason not to have plugins.

They would probably need a new plugin model that is itself suited for WinRT though, since the APIs and application lifecycle models are so different (and NPAPI/ActiveX/whatever plugins of today are really very general applications with some added hooks). Once that is in place though there is no real reason not to have plugins.

Depends on the particular plugin. Several Firefox plugins, in particular those that don't need to go outside of the browser environment, are simply written in Javascript. I would imagine that keeping support for these wouldn't be difficult.